JPS60162660A - Forming device for picture - Google Patents

Abstract

PURPOSE:To prevent the limit of the speed of recording by the number of revolution of a magnet and the number of magnetic poles, and to increase the speed of recording by attracting a toner by the magnet fitted on the back side of a recording surface in a recording medium and bringing the toner into contact with the nose of a recording electrode. CONSTITUTION:When an opposite electrode 9 is turned integrally in the direction D together with a recording medium 10, the toner 13 in a hopper 11 is detained in the vicinity of a recording electrode 15 by the magnetic field of a permanent magnet 17 fitted into the opposite electrode to form a toner chain 13a. When pulse voltage is applied to the recording electrode 15 by the pulse voltage applying circuit 20 under the state, the toner chain 13a is charged, and adheres on the record medium by Coulomb force. The particles of the toner 13 adhering on the record medium 10 are moved integrally together with the recording medium 10 as they are when the recording medium 10 is further turned, and escape from the magnetic field by the magnet 17. Accordingly, when the pulse voltage is applied selectively to each recording electrode 15 by the pulse voltage applying circuit 20, a dot by the toner 13 is printed where corresponding to the recording electrode, to which the pulse voltage is applied, in the recording medium 10.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention applies a voltage pulse to the recording electrode in a state in which magnetic toner is attracted by magnetic force and brought into contact with the recording electrode, and the toner is attracted by Coulomb force. The present invention relates to an image forming apparatus that performs recording by adhering to a recording medium.

Structure of a conventional example and its problems FIG. 1 shows a sectional view of a conventional image forming apparatus of this type.
In this figure, 1 is a fixedly installed sleeve, 2 is a magnet roll having an appropriate number of magnetic poles formed on the outer circumferential surface, and the magnet roll 2 is housed in the sleeve 1 and is shown in detail. It is designed to be rotated in the direction indicated by the arrow by a drive device that does not have the same function.

3 is outside sleeve 1 Ii! A recording electrode is fixed to the iI surface, 4 is a counter electrode facing the recording electrode 3, and 6 is a voltage pulse application circuit that applies a voltage pulse between the recording electrode 3 and the counter electrode 4. 6 is a recording medium such as electrostatic recording paper or plain paper, which is conveyed in the direction of arrow B by a conveying means (not shown). 7 is hopper, 8 is from hopper 7 to sleeve 1
This is a magnetic toner that is supplied onto the outer peripheral surface of the toner.

In this conventional device, when the magnetic roll 2 is rotated in the direction of the arrow by the drive device, the field transmitted by the roll 2 is also rotated, so that the toner 8 is drawn out from the hopper 7 onto the outer peripheral surface of the sleeve 1. , are conveyed along the outer circumferential surface in the direction of arrow C (in the direction opposite to the rotational direction of the tiIi stone roll 2), reach the tip of the recording electrode 3, and form a toner chain (toner particles are chained along the lines of magnetic force) on the tip of the recording electrode 3. form) 8a.

In this state, when a voltage pulse is applied between the recording electrode 3 and the counter electrode 4 by the voltage pulse application circuit 6, the toner particles at the tip of the toner chain 8a are moved by the Coulomb force to the magnet roll 2. It moves to the recording medium 6 against the magnetic force and is recorded in a dot-like layer on the medium e.

However, in this conventional device, the magnet roll 2
Along with the 0 rotation, the lines of magnetic force emitted from the roll 2 also rotate, so as the magnet roll rotates 20 times, the toner chain 8
The state of changes periodically.

That is, as shown in FIG. 1, the magnetic pole of the magnet roll 2, the tip of the recording electrode 3, and the counter electrode 4 are aligned in a straight line, and the lines of magnetic force passing through the tip of the recording electrode a are directed against the recording medium 6 and the counter electrode 4. When the toner chain 8a extends approximately vertically, the toner chain 8a also stands approximately vertically from the tip of the recording electrode 3 to the recording medium 6 and the counter electrode 4, and in this state, the recording electrode 3 and the counter electrode lfM4 A good image can be obtained by applying the voltage pulse between the two.

However, when the magnetic pole of the magnet roll 2 is shifted from the above-mentioned position, the direction of the magnetic field lines passing through the tip of the recording electrode 3 is no longer perpendicular to the recording medium 6 and the counter electrode 4, so that the toner chain 8a is also According to the lines of magnetic force, the toner chain 8a is inclined with respect to the recording medium 6 and the opposing ft pole 4, and the toner chain 8a is substantially not present on the tip of the recording electrode 3. Even if the voltage pulse is applied in such a state, a good image cannot be obtained.

Therefore, in this conventional device, the tii of the magnet roll 2
It was necessary to provide means for detecting the position of im, and to apply the voltage pulse at every timing when the magnetic pole of the magnet roll 2, the tip of the recording electrode 3, and the counter electrode 4 were aligned in a straight line. Therefore, the recording speed is limited by the number of rotations of the magnet roll 20 and the number of magnetic poles, and there is an inconvenience that it is impossible to increase the th1 recording speed.

OBJECT OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides an image forming apparatus that can increase the recording speed without being limited by the number of rotations of the magnet or the number of magnetic poles. The purpose is to provide.

Structure of the Invention The present invention achieves the above-mentioned object by fixing a magnet on the back side of the recording surface of a recording medium, and attracting toner supplied near the recording electrode by the magnetic force of the magnet and bringing it into contact with the tip of the recording electrode. This is what we aim to achieve.

Description of examples An embodiment of the present invention will be described below with reference to the drawings.

Figure M2 shows a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. In this figure, 9 is a cylindrical counter electrode made of aluminum alloy, which is a non-magnetic and conductive material; In the electrode 9, the rotation axis 9a is the opposite electrode 9.
It extends along the 0-axis melt. The counter electrode 9 is rotatably supported by a device body (not shown) via a rotating shaft 9a, and is rotated in the direction of the arrow (counterclockwise) by a drive device (not shown). .

Further, on the outer surface of the counter electrode 9, a layer of a recording medium 10 made of a dielectric material is provided. In addition, in this practical example, an opposing power line with the above-mentioned configuration is used. , e and recording medium 1
0 was obtained by applying alumite treatment to the outer peripheral surface of a mirror-finished aluminum pipe, but the recording medium 10 may also be formed by applying a dielectric material to the counter electrode 9.

Reference numeral 11 denotes a hopper made of a conductive material, and has a large opening 11a, and the counter electrode 9 is inserted into this opening 11.
It is arranged so that it is halfway into the hopper 11 from a. The lower end side of the upstream wall plate 11b of this hopper 11 is curved approximately along the counter electrode 9. Further, the lower end of the downstream wall plate 11c of the hopper 11 is attached to the lower end of the downstream wall plate 11c of the hopper 11. Moreover, in the hopper 11,
A magnetic toner 13 is contained therein.

A recording head 14 is fixed to the tip of the upstream wall plate 11b of the hopper 11, and a recording electrode 16 is provided on the recording head 14. Although only one recording electrode 16 is shown in the drawing, in reality, a large number of recording electrodes 15 are arranged along the direction parallel to the axial direction of the counter electrode 9 (direction perpendicular to the plane of the paper). It is provided. These many recording electrodes 16 each have their tips attached to the recording surface (outer peripheral surface) of the recording medium 10, for example.
．． They are opposed to each other with a gap 16t of about 0.6 to 0.2 mm interposed therebetween. A permanent magnet 17 is fixedly installed in the counter electrode e, and this magnet 17 is opposed to the tip of the recording electrode 16 via the counter electrode 9 and the recording medium 10.
A toner chain 13a' that attracts the toner 13 supplied near the tip of the recording electrode 16, contacts the tip of the recording electrode 16, and extends substantially in the normal direction to the recording medium 10.
i is designed to form.

Reference numeral 18 denotes a transfer roller made of conductive rubber, which is rotatably supported by the main body of the apparatus and is pressed against the recording medium 10 via a transfer paper 19 such as plain paper.

Reference numeral 20 denotes a voltage pulse application circuit, which can selectively apply voltage pulses to each recording electrode 16. 21
is a transfer power source, which applies a voltage to the transfer roller 18 with a polarity opposite to that of the voltage pulse applied to the recording electrode 16 from the voltage pulse application circuit 20. Note that the counter electrode 9 and the hopper 11 are grounded.

Next, the operation will be explained.

When the counter electrode 9 is rotated integrally with the recording medium 10 in the direction of the arrow by the driving device, the toner 13 in the hopper 11 tries to come out of the hopper 11 through the gap 16;
It is held near the recording electrode 15 by the M field of the magnet 17, and forms a toner chain 13a at a certain position.

Here, this toner chain 13a is connected to the recording medium 1.
0, and is in contact with the tip of the recording electrode 16. Note that the toner 13 and the recording medium 10
When the friction coefficient μ between the toner 13 and the recording medium 10 is large, the frictional force acting between the toner 13 and the recording medium 10 becomes large, and the toner 13 has a strong tendency to move together with the recording medium 1o.
Since it becomes difficult to stably form the toner chain 13a at a fixed position, it is preferable that the friction coefficient μ is as small as possible.

In the state where the toner chain 13a is formed as described above, the recording electrode 1 is
When a voltage pulse is applied to the toner chain 13a
is charged. As a result, the toner chain 13a
is attached to the recording medium by Coulomb force in addition to the magnetic force of the magnet 17. If the Coulomb force is made sufficiently large by appropriately selecting the level and pulse width of the voltage pulse, the particles of toner 13 that have adhered to the recording medium 10 as described above will be further removed from the recording medium 10. When it rotates, it moves integrally with the recording medium 10 and escapes the magnetic field caused by the magnet 17. It is enough).

Therefore, when a voltage pulse is selectively applied to each recording electrode 16 by the voltage pulse application circuit 20, a dot of the toner 13 is printed on the recording medium 1o at a position corresponding to the recording electrode to which the voltage pulse has been applied. That will happen.

Therefore, by selectively applying a voltage pulse to each recording electrode 16 from the voltage pulse application circuit 2o in accordance with the image signal, a toner image corresponding to the image signal is formed on the recording medium 10. This toner image is then transferred to the transfer row 21.
After being transferred onto the transfer paper 19 by the action of 8, it is fixed onto the transfer paper 19 by a fixing device (not shown) (arrow E).
indicates the rotating direction of the transfer roller 18, and arrow F indicates the advancing direction of the transfer paper 19), thereby obtaining a hard copy corresponding to the image signal.

Note that even after the transfer by the transfer row 216, residual toner remaining on the recording medium 10 is transferred to the intermediate recording medium 1.
0 returns into the hopper 11 through the gap 12 by further rotation. Then, the electric charges accumulated in the residual toner are discharged to the ground through the toner 13 in the hopper 11 and the hopper 11, so that the residual toner 13
The toner returns to its initial uncharged state, and as the recording medium 10 rotates, it mixes with other toner in the hopper 11 and is again supplied toward the recording electrode 15.

Here, in this image forming apparatus, the magnet 17 is fixed, and the magnetic field by this magnet 17 is also fixed, so the state of the toner chain 13a can always be maintained in a state where a good image can be recorded. There is no need to apply a voltage pulse to the recording electrode in synchronization with the rotation of the magnet roll as in the case of the conventional device, and the recording speed is not limited by the number of rotations of the magnet roll or the number of magnetic poles. Recording speed can be increased.

In the above embodiment, the recording medium 10 and the counter electrode 9 are integral and cylindrical, but in the present invention,
The recording medium and the counter electrode do not necessarily have to be integral, nor do they have to be cylindrical. For example, the recording medium may be shaped like an endless belt and rotated in a circular manner, while the counter electrode may be fixedly installed separately from the recording medium. It's okay.

Further, in the embodiment described above, a transfer means such as the transfer roller 18 is provided, but if the apparatus does not require a hard copy, the transfer means is not necessary.

Effects of the Invention According to the present invention, since the magnet is fixedly installed on the back side of the recording surface of the recording medium, the recording speed is not limited by the rotating part of the magnet or the number of magnetic poles, and the recording speed can be increased. You can get the immersive effect of being able to do it.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional image forming apparatus, and FIG. 2 is a sectional view of an image forming apparatus according to an embodiment of the present invention. 9... Counter electrode, 10... Recording medium,
11...hopper, 13...toner,
15...recording electrode, bare...magnet, 2
0...Voltage pulse application circuit.

Claims (1)

[Claims] A recording electrode facing the recording surface of the recording medium with a gap therebetween, a counter electrode facing the recording electrode on the back side of the recording surface of the recording medium, and magnetic toner in the vicinity of the recording electrode. supplying means; a magnet fixedly installed on the back side of the recording surface of the recording medium to attract the toner by magnetic force and bring it into contact with the tip of the recording electrode; and between the recording electrode and the counter electrode. an image forming apparatus comprising means for applying a voltage pulse to the image forming apparatus.